#KopiaLens vs Duplicati

Duplicati is a free, open-core backup app with a long history, a web UI and dozens of storage backends. KopiaLens is a backup app on the Kopia engine whose difference is seeing inside the repository: what each folder really costs, what is safe to remove, and what a cleanup would free. Both back up a computer on a schedule, in different backup formats.

	KopiaLens	Duplicati
What it is	A backup app that shows what is inside your backups	A free, open-core backup app with a local web UI
Backups with	Kopia repositories	Duplicati's own backup format
Platforms	Windows, macOS, Linux, Docker and NAS, Home Assistant, browser	Windows, macOS, Linux, Docker
Scheduled backups	Yes	Yes
Browse and restore	Yes	Yes
Storage backends	Kopia's list, including S3, B2, Azure, Google Cloud, WebDAV, SFTP and rclone	Dozens, including S3, B2, IDrive e2, Azure, Google Cloud, Drive, OneDrive, SFTP and WebDAV
Per-folder size after dedup	Yes	No
Reclaimable space and removal previews	Yes	No
Remove files from old snapshots	Pro, guided with previews	purge command; all versions by default, no reclaim preview
Full-disk imaging	No	Yes, paid module
Price (November 2026)	Free; Pro $20/year or $50 lifetime at launch pricing	Core free; optional console $2/machine/month; imaging and Microsoft 365 or Google Workspace modules need a subscription

#What KopiaLens adds

• Where the space goes. Per-folder physical size after deduplication, reclaimable space, churn, and a retention simulation. Duplicati reports backup sizes; it does not show what each folder really costs.
• Guided removal (Pro). See which snapshots hold a file, preview the removal, and see the space it frees before anything is deleted.
• Search across every snapshot. Find every version of a file in one search.
• The Kopia engine. Deduplication, compression, encryption and error correction, in a repository that other Kopia tools can open. Nothing to rebuild before a restore: the repository holds everything, with no separate local database.

#What Duplicati does well

• Backend breadth. If a storage provider exists, Duplicati probably supports it. That is a real advantage when your destination is unusual.
• Imaging and application backups. Full-disk imaging, Microsoft 365 and Google Workspace backup are available as source-available modules, with a subscription for production use.
• Runs anywhere. The web UI works on a headless server, a NAS or Docker, and VSS/LVM snapshots handle open files.
• A big, long-lived community. More than 50,000 users by Duplicati's own count, years of forum answers, and a stable 2.x line. The 2.4 line brought full-disk imaging to all three platforms and added PAR2 parity; 2.4.1 (October 2026) added restore tests and delta backups for Microsoft 365 and Google Workspace.
• A free core. The engine, server, CLI and web UI are MIT-licensed and free to use without an account.

#Who should pick which

Pick Duplicati when you need imaging, Microsoft 365 or Google Workspace backup, an unusual storage backend, a headless web UI, or the largest free feature set. If it already works well for you, there's little reason to move.

Pick KopiaLens when the problem is the size of your backups: you want to see which folder is responsible, find an old file quickly, or remove junk from old snapshots without deleting your history.

#Switching

KopiaLens cannot open a Duplicati repository. Moving means starting a new Kopia repository in KopiaLens and keeping Duplicati installed for the old backups until their retention period ends. There is no re-upload of the old data and no conversion tool. Plan the switch at a point where a fresh full backup is acceptable.

The backup app is free. Pro, for cleanup, costs $20 a year or $50 lifetime at launch pricing. Download KopiaLens or see the plans.

Prices and product facts checked November 2026. Spotted something out of date? Email support@kopialens.com and we'll fix it.